Disks lists all the current storage
devices in the left pane of the window. When you select one of these devices,
detailed information about it is displayed in the right pane: its partitions,
its brand, its size, etc.

Find which device contains the persistent volume. It should have two
partitions, one labeled Tails, and
another one labeled TailsData which
corresponds to the persistent volume.

In the right pane, click on the persistent volume partition, labeled
TailsData.